Multiple aerial switch



Nov. 24, 1936 c. E. GERHARD MULTIPLE AERIAL SWITCH Filed Oct. 10, 1955 Patented Nov. 24, 1936 UNITED STATES PATENT OFFICE MULTIPLE AERIAL SWITCH Charles E. Gerhard, Philadelphia,

to Philco Radio & Television Corporation,

Pa., assignor Phil- 6 Claims.

This invention relates to electrical signaling systems and, more particularly, to radio receiving systems wherein it is desired to use one of a plurality of radio sets with a single antenna and to automatically connect only one radio receiving set to the antenna at any one time.

One object of the invention is to provide a novel system by means of which an antenna may be connected automatically to a radio receiver when the receiver is turned on or energized and the antenna may be disconnected automatically from the receiver when the receiver is turned ofi or deenergized.

Another object of the invention is to provide a compact device which may be readily connected electrically to an antenna and to a radio receiving set and by means of which the above stated result may be accomplished.

The invention is particularly adapted for use in any instance where it is desired to use a plurality of radio receiving sets with a single antenna. For example, in stores or other places, where it is desired to demonstrate radio receivers using a single antenna for a plurality of receivers, it is possible by means of the present invention to selectively connect any one of the radio receivers to the antenna automatically by merely turning on the radio receiver to be demonstrated, thus eliminating the necessity of several switching operations or of making electrical connections. The invention is also adapted for use in homes where two or more radio receivers are used and it is desired to use a single antenna for the several receivers. These particular adaptations and others will be more clearly apparent as the description proceeds.

The invention may be clearly understood by reference to the accompanying drawing wherein there is illustrated a single preferred embodiment of the invention.

In the drawing:

Fig. 1 is a diagrammatic illustration of the electrical system provided by the invention;

Fig. 2 is a front face view of the automatic switching device provided by the invention;

Fig. 3 is a rear View of the mechanism of the device with the back of the casing or housing removed; and

Fig. 4 is a sectional view of the device taken along line 4-4 of Fig. 3.

Referring particularly to Fig. 1 of the drawing, thereis shown an antenna l and a conventional transmission line 2 therefor. Conventional radio receiving sets are shown at 3 and 4, two such sets being illustrated for the purpose of disclosure of the invention. It will be understood, however, that any number of radio receiving sets may be employed. A suitable source of electrical energy is illustrated at 5, which source may be the conventional current supply line of a building such 5 as a store, dwelling, etc. In accordance with the invention, there is provided a device 6 associated with each of the radio receivers, as will be described in detail hereinafter.

As is well known, a radio receiver is usually 10 energized by some electrical supply source which may consist of batteries or any other conventional source. The energization of the radio receiver is controlled by a switch at the receiver. In the illustration of Fig. l, the energizing switches of the radio receivers 3 and 4 are shown, respectively, at 1 and 8. The receivers are actuated by high frequency signals picked up by the antenna i, which signals build up voltages across the tuning units of the radio receivers, such units being shown at 9 and lil, respectively. In a conventional radio receiver, the tuning unit may comprise an inductance or radio frequency transformer. For reception of signals in the broadcast band, it is customary to design this unit so that it has relatively high inductance. For reception of signals in the short-wave bands, however, the said inductance is materially reduced. Thus, in one case the unit presents high impedance to signals in the broadcast band, while in the other case, the unit presents low impedance to signals in the broadcast band. Thus, if the radio receiver 3 were adjusted to receive signals in the broadcast band and if the radio receiver 4 were adjusted to receive signals in the short-wave band and if the two receivers were both connected to the same antenna, the tuning unit 9 of receiver 3 would be eiiectively short-circuited by the tuning unit If) of receiver 4, and the reproduction of signals in the broadcast band by the receiver 3 would be deleteriously affected. Likewise, even if both of the radio receivers were adjusted to receive signals within one frequency range and even if both of the tuning units 9 and II] had substantially the same inductance, nevertheless the performance of each set would be materially afiected by the presence of the other set. For this reason, it has been customary, when using a plurality of radio receivers, to manually disconnect all of the receivers from the antenna except the one being used or demonstrated. By means of the present invention, this maybe accomplished automatically by the actuation of the conventional energizing switches l and 8.

The devices 6 shown in Fig. 1 are identical and these devices, as well as the parts thereof, are designated by corresponding reference characters. A description of one of these devices and its cooperative association with the other elements of the system will suffice. The device comprises essentially a relay II having an energizing winding I2 and an armature I3. The winding I2 is connected in series in the energy supply circuit I4 of the radio receiver. Thus, the winding I2 is connected in series with the energizing switch at the receiver. The armature I3 comprises contacts I5 and I6 which are adapted to close the antenna lead-in circuit IT. The contacts I5 and I6 are normally maintained in opened position, as shown, by a spring I8, the armature being pivoted at the point I9.

It will be seen that closure of switch I, for example, to energize the radio receiver 3 will, at the same time, energize the relay causing the contacts I5 and I6 thereof to close and thus connecting the receiver 3 to the antenna. The relay winding is designed to present negligible impedance to the energizing current, so that substantially full line voltage is applied to the rei ceiver. When the switch 1 is opened to deenergize the receiver, the relay is automatically deenergized and the spring I8 causes the contacts I5 and I6 to open, thus automatically disconnecting the receiver from the antenna. In the same manner, the receiver 4 is automatically connected to the antenna when the switch 8 is closed and is automatically disconnected from the antenna when the switch 8 is opened. As stated above, any number of radio receivers may be used with the antenna, each receiver having associated with it a device 6, as illustrated, so that any one of the receivers may be automatically connected to the antenna and disconnected therefrom.-

The device 6 preferably takes the form of a single compact unithaving suitable electrical connectors to facilitate connection of the device to the associated elements or apparatus. This will be understood from the following description of the preferred form of the unitary device.

In the illustration of Fig. 1, radio receivers have been shown connected to the antenna I through the units 6 by means of the transmission line 2 which preferably comprises a low impedance line Whose conductors are twisted as illustrated. Such a transmission line serves to reducenoise interference which might be picked up by the antenna lead-in. While this arrangement is preferred, it Will be understood that any conventional antenna and lead-in which may comprise one or more wires, may be used; It will be noted also that the electrical connections to the radio receivers are shown as comprising twisted conductors and, while this is preferred, it is not necessary. Furthermore, it is generally desirable to separate the high frequency signal leads from the power leads.

The relay switches comprising contactors I5 and It should preferably be such as to form good contact of low resistance when the switches are closed and the switches should have very low inter-element capacity when open so that they will not act as a short-circuit to the high fre-- quency short-wave signals.

Referring now to Figs. 2 to 4; the device 6 preferably comprises a two-part casing or housing having a front section 20 and a box-like back section 2| removably associated with the front section. A conventional plug receptacle 22 is mounted upon the front section of the casing and is adapted to receive the usual plug which is attached to the power supply leads-of a radio receiving set, thus connecting the radio set to the device 6. Insulated terminals 23 and 24 are also mounted upon the front section 20 and are adapted to receive the leads from the antenna transmission line or lead-in.

As shown more clearly in Figs. 3 and 4, a pair of inverted U-shapecl brackets 25 and 26 are attached to the front section 20 of the casing, the receptacle 22 being secured to these supports and insulated therefrom by meansof the plate 2! formed. of insulating material. At the rear of the supporting brackets 25 and 26, there is attached a similar plate 28 of insulating material to which are secured terminals 29 and 30 having prongs 3I and 32' adapted for insertion in the usual outlet receptacle or convenience outlet. The prongs 3| and 32 extend through openings in the back section.

A supporting bracket 33 is mounted upon the brackets 25 and 26 and serves to support the elements ofrelay II. The coil I2 of the relay is secured to the lower part of bracket 33 and the coil in turn supports insulating plate 34 which carries stationary contacts 35 and 36.

The relay armature comprises a plate 31 which is pivotally mounted upon bracket 33 at the point I9. Plate 31 carries an insulating member 38 which, in turn,rcarries the movable contact arms I5 and I6 above mentioned. These contact arms are normally maintained out of engagement with the stationary contacts 35 and 36 by the spring I8, above mentioned, which is secured between the armature plate 31 and the bracket 33.

From the illustration of Fig. 1, it will be seen that the prong 3| is connected to one extremity of the relay Winding I2, the other extremity of the winding being connected to one of the con! tacts of the plug receptacle 22. The prong 32 is connected directly to the other contact of recep tacle 22. Thus, the relay winding, which presents low impedance to the energizingcurrent, is connected serially in the power supply circuit-of an associated receiver whenthe prongs 3I and 32 are inserted in a power supply outlet and when the plug attached to the power supply leads of the receiver is inserted in receptacle 22;' The terminals 23 and 24 are connected electrically to the contact arms I5 and I6, while the stationary contacts 35 and 36 have electrical conductors connected thereto which extend through an opening 39 in the front face of the device in the'form of a two-conductor cable 40. These conductors may be connected to the terminals provided on the radio receiving set for the antenna.

It will be seen that this device iscompact and adapted for convenient use. By simply removing the box-like back section 2I of the casing,'the various parts of the device are exposedand may be readilyreplaced whenever necessary. Moreover, the two sections of the casing may be held together by two screws, the front section having flanged side edges which overlap the sides of the back section. A screw on each side secures the back section to said flanges.

Although it is capable of various usages as above mentioned, the invention is particularly adapted for use in stores in the demonstration of radio sets to prospective buyers. With a plurality of radio sets connected to a single antenna through the devices 6, as. illustrated in. Fig. 1, the demonstrator or salesman may automatically'connect any one of :the radio receivers to the antenna by simply turning the receiver on in the usual fashion. Moreover, only that. set which is turned on is connected to the antenna, sothat the proper demonstration of the particular set may be given. Thus, there is eliminated any necessity for the demonstrator or salesman to make any other electrical connections in order to demonstrate the various radio sets.

In the sale of any article, it is desirable that the interest of the prospective buyer be constantly maintained and this requires uninterrupted contact of the salesman with the buyer. If the radio set salesman is handicapped by having to make electrical connections, in order to demonstrate various sets to a customer, during his sales efforts, the interest of the customer is quite apt to lag and a sale, which would otherwise have been effected, might be lost. By means of the present invention, the salesman or demonstrator enjoys uninterrupted contact with the customer and is better able to demonstrate various radio receiving sets.

It will also be seen that the invention is highly desirable and advantageous in any instance where it is desired to use a plurality of radio receivers with a single antenna. While the invention is directed particularly to radio receivers, it will be understood that it is applicable in any case where a plurality of signal receiving devices are employed. Although the invention has been illustrated in a preferred specific form, it will be understood that it is not thus limited and may be practiced with various modifications such as fall within the scope of the appended claims.

I claim:

1. In an electrical signaling system, a source of electrical signals, a plurality of signal receiving devices, means for supplying electrical power to each of said signal receiving devices, and means associated with each of said devices and controllable by the power-supply means thereof, for selectively connecting a signal receiving device to said source when said device is energized and for disconnecting said source from said device when said device is deenergized.

2. In a radio receiving system, an antenna for collecting high frequency signals, a plurality of radio receivers, means including a switch for supplying electrical power to each of said receivers, and means associated with each of said receivers and controllable by the power-supply means thereof, for selectively connecting a receiver to said antenna when said receiver is energized and for disconnecting said antenna from said receiver when said receiver is deenergized, said last means comprising a relay having an energizing winding connected in series with said switch, and electrical contacts controlled by said winding and connected in the antenna lead-in of the associated receiver.

3. A device for use with a signal receiving device to enable the connection of said receiving device at will to a source of electrical signals, comprising a casing, a pair of contact prongs extending from said casing for insertion in an outlet receptacle, a two-contact receptacle on said casing adapted to receive a plug on a conductor cord. connected to power supply terminals on said receiving device, means within said casing connecting one of said prongs to one of said receptacle contacts, a relay within said casing comprising an energizing winding connected between the other of said prongs and the other of said receptacle contacts, and circuit means within said casing controllable by said relay for connecting said source to said receiving device when the latter is energized and for disconnecting the source from the receiving device when the latter is deenergized.

4. A device for use with a signal receiving device to enable the connection of said receiving device at will to a source of electrical signals, comprising a casing, a pair of contact prongs extending from said casing for insertion in an outlet receptacle, a two-contact receptacle on said casing adapted to receive a plug on a conductor cord connected to power-supply terminals on said receiving device, means within said casing connecting one of said prongs to one of said receptacle contacts, a relay within said casing comprising an energizing winding connected between the other of said prongs and the other of said receptacle contacts, a pair of terminals on said casing to which a transmission line from said source may be connected, a pair of conductors extending from said casing for connection to signal input terminals on said receiving device, and means within said casing controllable by said relay for connecting said terminals to said conductors when the receiving device is energized and for disconnecting said terminals from said conductors when the receiving device is deenergized.

5. A device for connecting a signal receiving device at will to a source of electrical signals, comprising a casing, a pair of input elements on said casing adapted to be connected across a power-supply source, a pair of output elements on said casing adapted to be connected to the power-supply portion of said. receiving device, means within said casing connecting one of said input elements to one of said output elements, a relay within said casing comprising an energizing winding connected between the other input element and the other output element, and circuit means within said casing controllable by said relay for connecting said source to said receiving device when the latter is energized and for disconnecting the source from the receiving device when the latter is deenergized.

6. A device for connecting a signal receiving device at will to a source of electrical signals, comprising a casing, a pair of input elements on said casing adapted to be connected across a power-supply source, a pair of output elements on said casing adapted to be connected to the power-supply portion of said receiving device, means within said casing connecting one of said input elements to one of said output elements, a relay within said casing comprising an energizing winding connected between the other input element and the other output element, a pair of terminals on said casing to which a transmission line from said source may be connected, a pair of conductors extending from said casing for connection to signal input terminals on said receiving device, and means within said casing controllable by said relay for connecting said terminals to said conductors when the receiving device is energized and for disconnecting said terminals from said conductors when the receiving device is deenergized.

CHARLES E. GERHARD. 

